Author: blass uri
Date: 10:58:04 10/04/98
Go up one level in this thread
On October 04, 1998 at 13:37:09, blass uri wrote: > >On October 04, 1998 at 13:06:30, Robert Hyatt wrote: > >>On October 04, 1998 at 11:51:20, blass uri wrote: >> >>> >>>On October 04, 1998 at 10:00:09, Robert Hyatt wrote: >>> >>>>On October 04, 1998 at 05:24:42, blass uri wrote: >>>> >>>>> >>>>>On October 03, 1998 at 22:07:23, Robert Hyatt wrote: >>>>> >>>>> >It really wouldn't help, because this would reduce the size of the current >>>>>>tablebases by 1/4, because they use 8 bit values. >>>>> >>>>>How can you use 8 bit values >>>>>only to store the move you may need 6 bits because you may have more than 32 >>>>>legal moves even only with king and queen. >>>>> >>>>>do you mean 8 bits only to store the result and that the tablebases use more >>>>>than 8 bits for position(8 bits for result and 5 or 6 bits for the move)? >>>>> >>>>>you can save space in the harddisk by not storing the result and computing it by >>>>>playing the right moves against yourself but in this case you are slower. >>>>> >>>>>Uri >>>> >>>> >>>> >>>>there are no "moves" in the database. It is a huge stream of bytes indexed by >>>>a "Godel" number that is simply a concatenation of the squares each piece sit >>>>on. IE let's number the squares a1=0... h8=63. put the white knight on a1, >>>>white king on b1, white bishop on c1 and black king on d1. All we do is take >>>>the 4 squares and compute b1<<18 + a1<<12 + c1<<6 + d1... which gives us a >>>>number that indexes into the database, and the value we find there is +Mate in >>>>N, -Mate in N, or Draw (0). >>>> >>>>No moves, no pieces, etc. The pieces (the squares they stand on) form the >>>>key, the result at that position is how many moves to mate, or else "draw" >>> >>>I understand >>>You can use the exact result of mate in N to compute the move. >>> >>>I think that 7 bytes may be enough to store the result if instead of storing >>>mate in how many moves you store only the number of moves before the next >>>capture or the next moving of a pawn >>>because of the 50 moves rule you have only 101 possible results >>>draw or win in 1-50 moves for you or win in 1-50 moves for the opponent >>> >>>Uri >> >> >>I assume you mean "seven bits". But this doesn't tell me anything about how >>to choose between two moves in the tree, when one is mate in 10 and one is >>mate in 30. And if I keep choosing mate in 30, I encounter problems, because >>I can end up drawing by the 50 move rule, since the "distance to conversion" >>doesn't factor in the moves played *before* this position was reached, only >>what happens *after* this position was reached... >> >>In any case, distance to mate is trivial to use, and never screws up. > >theoretically distance to mate may cause problems becuase if one is mate in 70 >that is practically a draw because of the 50 move rule and the second is mate in >80 that is not a draw because there is a capture after 40 moves than mate in 80 >is the right move. I understand that the tablebases in the first case may say draw and solve this problem > >I do not understand how distance to the next capture or moving a pawn may cause >problems because what happened before is not relevant I think if you imagine the target is not to do mate as soon as possible but to do capture that lead to winning or moving a pawn that lead to winning then there is no problem because the distance to win is always become shorter and after a capture you have a new game Uri > >> I can >>show you cases where fritz lost in drawn positions because it took the move >>that led to the "most distant conversion" and overlooked a mate in 2 on the >>board... > >I want to see > >Uri
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